CN113339246A - Flow calibration method and flow calibration system of piezoelectric pump - Google Patents

Flow calibration method and flow calibration system of piezoelectric pump Download PDF

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Publication number
CN113339246A
CN113339246A CN202010137825.3A CN202010137825A CN113339246A CN 113339246 A CN113339246 A CN 113339246A CN 202010137825 A CN202010137825 A CN 202010137825A CN 113339246 A CN113339246 A CN 113339246A
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piezoelectric pump
calibrated
flow
preset
voltage frequency
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CN113339246B (en
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熊小川
刘东敏
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Shenzhen Meimeimeichuangyi Medical Technology Co ltd
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Shenzhen Meimeimeichuangyi Medical Technology Co ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B51/00—Testing machines, pumps, or pumping installations
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/06—Control using electricity

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)

Abstract

The invention relates to a flow calibration method and a flow calibration system of a piezoelectric pump. The flow calibration method of the piezoelectric pump comprises the following steps: under the preset driving voltage frequency, N first flow values output by the piezoelectric pump to be calibrated within a preset range of performance indexes are measured, wherein the performance indexes are voltage amplitude values or duty ratios; determining a calibration relation according to the performance index and the first flow value, wherein the calibration relation is a corresponding relation between the performance index and the first flow value under the driving voltage frequency; and determining a standard value of a corresponding performance index of the piezoelectric pump to be calibrated under the target flow according to the calibration relation, and determining the flow value output by the piezoelectric pump to be calibrated under the preset driving voltage frequency and the standard value to obtain the calibrated flow of the piezoelectric pump to be calibrated. The piezoelectric pump is calibrated by adopting the method so as to improve the consistency of the control effects of different piezoelectric pumps.

Description

Flow calibration method and flow calibration system of piezoelectric pump
Technical Field
The invention relates to the technical field of metering test, in particular to a flow calibration method and a flow calibration system of a piezoelectric pump.
Background
Piezoelectric pumps are core components in microfluidic systems, can be widely applied to the fields of chemical analysis, drug delivery, and the like, and have been rapidly developed in recent years. At present, the flow control of the piezoelectric pump is mainly realized by adjusting the voltage of the piezoelectric vibrator or adjusting the working frequency. However, since the output flow rate of the piezoelectric pump is highly nonlinear to the frequency of the driving voltage and the output flow rate is nonlinear to the voltage amplitude in a positive correlation, it is difficult to accurately control the flow rate of the piezoelectric pump by adjusting the voltage of the piezoelectric vibrator or adjusting the operating frequency. Some researches improve the accuracy of flow control by a closed-loop control mode, but because the individual characteristics of the piezoelectric pumps (such as voltage frequency and flow characteristics and voltage amplitude and flow characteristics) are large, the consistency of the control effects of different piezoelectric pumps is still difficult to ensure.
Disclosure of Invention
Based on this, it is necessary to provide a flow calibration method for a piezoelectric pump, which is used to calibrate the piezoelectric pump so as to improve the consistency of the control effects of different piezoelectric pumps.
In addition, a flow calibration system of the piezoelectric pump is further provided.
A flow calibration method of a piezoelectric pump comprises the following steps:
under a preset driving voltage frequency, measuring N first flow values output by the piezoelectric pump to be calibrated within a preset range of a performance index, wherein the piezoelectric pump to be calibrated meets the following formula under the preset driving voltage frequency: f2= F1 × (1 + η), where F2 is a maximum flow rate output by the piezoelectric pump to be calibrated at the preset driving voltage frequency, F1 is a rated flow rate of the piezoelectric pump to be calibrated, η is a flow rate increase percentage, and the performance index is a voltage amplitude or a duty ratio;
determining a calibration relation according to the performance index and the first flow value, wherein the calibration relation is a corresponding relation between the performance index and the first flow value under the driving voltage frequency; and
and determining a standard value of the performance index corresponding to the piezoelectric pump to be calibrated under the target flow according to the calibration relation, and then measuring the flow value output by the piezoelectric pump to be calibrated under the preset driving voltage frequency and the standard value to obtain the calibrated flow of the piezoelectric pump to be calibrated.
According to the flow calibration method of the piezoelectric pump, N first flow values output by the piezoelectric pump to be calibrated within a preset range of performance indexes are measured under the preset driving voltage frequency, the performance indexes are voltage amplitude values or duty ratios, a corresponding relation between the performance indexes and the first flow values is established, and then the calibrated flow is obtained by calibrating each piezoelectric pump through the corresponding relation, so that the problem that response time and fluctuation degree of a control system are uncertain due to large individual performance difference of the piezoelectric pump is solved, and consistency of control effects of different piezoelectric pumps is improved.
In one embodiment, the step of determining, at the preset driving voltage frequency, N first flow values output by the piezoelectric pump to be calibrated within a preset range of the performance index includes: inputting a first driving signal to the piezoelectric pump to be calibrated, setting the voltage frequency of the first driving signal as the preset driving voltage frequency, and setting the performance index of the first driving signal as N different preset values respectively, to obtain the first flow value output by the piezoelectric pump to be calibrated at each preset value, where the N preset values are monotonously changed within the preset range of the performance index.
In one embodiment, N of the preset values monotonically increase within the preset range of the performance indicator.
In one embodiment, the preset range is an operating range of the performance index of the piezoelectric pump to be calibrated.
In one embodiment, after the step of determining the calibration relationship according to the performance indicator and the first flow value, the method further includes the step of verifying the calibration relationship: and comparing the N first flow values corresponding to the N preset values, wherein if the variation trend of the N first flow values is consistent with the variation trend of the N corresponding first preset values, the calibration relation is valid.
In one embodiment, before the step of determining N first flow values output by the piezoelectric pump to be calibrated within a preset range of the performance index at the preset driving voltage frequency, the method further includes a step of searching for the preset driving voltage frequency:
under the conditions of the maximum voltage amplitude and the maximum duty ratio, measuring M second flow values output by the piezoelectric pump to be calibrated in the working range of the driving voltage frequency; and
comparing the second flow value corresponding to each driving voltage frequency, wherein if the second flow value can satisfy the formula corresponding to F2, the driving voltage frequency corresponding to the second flow value is the preset driving voltage frequency.
In one embodiment, the step of determining, at the maximum voltage amplitude and the maximum duty cycle, M second flow values output by the piezoelectric pump to be calibrated in the operating range of the driving voltage frequency includes: and inputting a second driving signal to the piezoelectric pump to be calibrated under the maximum voltage amplitude and the maximum duty ratio, and setting the driving voltage frequency of the second driving signal to M different preset frequency values respectively, so as to obtain the second flow value output by the piezoelectric pump to be calibrated under each preset frequency value, wherein the M preset frequency values are monotonically increased within the working range of the driving voltage frequency.
A flow calibration system for a piezoelectric pump, comprising:
the control module can apply a driving signal to the piezoelectric pump to be calibrated to drive the piezoelectric pump to be calibrated, and can control the driving voltage frequency and the performance index of the driving signal, wherein the performance index is the voltage amplitude or the duty ratio; and
the flow detection module is connected with the control module and is used for detecting the flow value of the piezoelectric pump to be calibrated and transmitting the detected flow value of the piezoelectric pump to be calibrated to the control module;
the control module can control the voltage frequency of the driving signal to be a preset driving voltage frequency, and can control the performance index of the driving signal to be in a preset range to drive the piezoelectric pump to be calibrated, the flow detection module can determine N first flow values output by the piezoelectric pump to be calibrated in the preset driving voltage frequency and the preset range of the performance index, and transmit the N first flow values to the control module, and the piezoelectric pump to be calibrated satisfies the following formula at the preset driving voltage frequency: f2= F1 × (1 + η), where F2 is the maximum flow rate output by the piezoelectric pump to be calibrated at the preset driving voltage frequency, F1 is the rated flow rate of the piezoelectric pump to be calibrated, and η is the percentage of flow rate increase; the control module can determine a calibration relation according to the performance index and the first flow value, wherein the calibration relation is a corresponding relation between the performance index and the first flow value under the driving voltage frequency; the control module can determine a standard value of the performance index corresponding to the piezoelectric pump to be calibrated under the target flow according to the calibration relation, then can control the driving voltage frequency of the driving signal to be the preset driving voltage frequency, control the performance index of the driving signal to be the standard value, drive the piezoelectric pump to be calibrated, and obtain the calibrated flow of the piezoelectric pump to be calibrated through the flow detection module.
In one embodiment, the device further comprises a display module, wherein the display module is connected with the control module, and the display module can generate a start calibration instruction or a stop calibration instruction to the control module and can receive and display a signal transmitted by the control module.
In one embodiment, the calibration device further comprises a storage module, wherein the storage module is connected with the control module and can receive and store the calibration relation transmitted by the control module.
Drawings
Fig. 1 is a schematic structural diagram of a flow calibration system of a piezoelectric pump.
Fig. 2 is a graph comparing the flow rate and the response time during the closed-loop control before the calibration of the three piezoelectric pumps to be calibrated in example 1.
Fig. 3 is a graph comparing the flow rate and the response time during the closed-loop control process after the calibration of the three piezoelectric pumps to be calibrated in example 1.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
The flow calibration method for the piezoelectric pump can calibrate the piezoelectric pump so as to improve the consistency of control effects of different piezoelectric pumps. The flow calibration method of the piezoelectric pump comprises the following steps of S110-S130:
s110, under the preset driving voltage frequency, N first flow values output by the piezoelectric pump to be calibrated within the preset range of the performance index are measured.
The piezoelectric pump to be calibrated meets the following formula under the preset driving voltage frequency: f2= F1 × (1 + η), F2 is the maximum flow rate output by the piezoelectric pump to be calibrated at the preset driving voltage frequency, F1 is the rated flow rate of the piezoelectric pump to be calibrated, and η is the flow rate increase percentage. The preset driving voltage frequency is set so that the maximum flow (i.e., F2) output by the piezoelectric pump to be calibrated at the preset driving voltage frequency meets the product requirement and is not too large. Further, η is 20%. η is not limited to 20%, and may be set as needed.
It should be noted that, in practical operation, there is a certain error between F2 actually obtained by the piezoelectric pump to be calibrated at the preset driving voltage frequency and F2 obtained by presetting η and calculating according to the formula F2= F1 × (1 + η), where the error is denoted as E, and when the error is-5% or more and E or less than 5%, the requirement of the preset driving voltage frequency is still met, that is, (F2)Practice of- F2Computing）/ F2Computing= E, -5% or more and E5% or less, wherein F2Practice ofF2, F2 actually obtained for the piezoelectric pump to be calibrated under the preset driving voltage frequencyComputingF2 is calculated by presetting η and according to the formula F2= F1 × (1 + η).
Wherein, the performance index is a voltage amplitude or a duty ratio. It should be noted that the driving signal for driving the piezoelectric pump to be calibrated is a sinusoidal signal, and the performance index is a voltage. The drive signal for driving the piezoelectric pump to be calibrated is a PWM (Pulse width modulation) signal, and the performance index is a duty ratio.
In one embodiment, the step of determining N first flow values output by the piezoelectric pump to be calibrated within a preset range of the performance index at a preset driving voltage frequency comprises: inputting a first driving signal to the piezoelectric pump to be calibrated, setting the voltage frequency of the first driving signal as a preset driving voltage frequency, and setting the performance index of the first driving signal as N different preset values respectively, so as to obtain a first flow value output by the piezoelectric pump to be calibrated under each preset value, wherein the N preset values are monotonously changed within a preset range of the performance index. According to the research, the point-to-point duty ratio voltage or the point-to-point voltage amplitude is calibrated, so that the response speed can be increased, and the time for controlling the flow to enter a steady state can be shortened.
Wherein the N preset values monotonically increase within a preset range of the performance index. The preset range is the working range of the performance index of the piezoelectric pump to be calibrated. The operating range refers to a range formed by a minimum value to a maximum value of the performance index in which the piezoelectric pump to be calibrated can operate. It should be noted that the N preset values are not limited to monotonically increasing values, but may also be monotonically decreasing values within the preset range of the performance index.
Further, N is 10-30. N is not limited to 10 to 30, and may be set as needed. Further, N is 10. This arrangement enables the resolution of the calibration data to meet the control requirements and also enables the calibration process time to be as short as possible.
In a specific example, the performance index is a duty ratio, and the preset range is 0% -50%. Further, the N preset values monotonically increase with a step size of 5% within the preset range of the performance index. The step size is not limited to 5%, and may be set as needed.
In a specific example, the performance index is a voltage amplitude, and the preset range is 0-V. Where V is the maximum voltage amplitude of the piezoelectric pump or the maximum voltage amplitude that the driving circuit can provide). Further, the N preset values monotonically increase with a step size of 0.1V within the preset range of the performance index. The step size is not limited to 0.1V, and may be set as needed.
It should be noted that the driving signal for each value of the performance index needs to be maintained for a certain time to ensure that the output first flow value is stable. After the first flow value is output and stabilized, the flow data is collected, and the data collection can be performed after the flow data is subjected to digital filtering processing. The digital filtering processing method may be, for example, mean filtering, or other digital filtering methods. The drive signal for each value of the performance indicator needs to be maintained for 1.5 seconds. Wherein the first 1 second is used to stabilize the first flow value and the second 0.5 second is used to collect data for the first flow value.
In one embodiment, before the step of measuring N first flow values output by the piezoelectric pump to be calibrated within the preset range of the performance index under the preset driving voltage frequency, the method further includes steps S101 to S102 of finding the preset driving voltage frequency:
s101, under the conditions of the maximum voltage amplitude and the maximum duty ratio, M second flow values output by the piezoelectric pump to be calibrated in the working range of the driving voltage frequency are measured.
Specifically, S101 includes: and inputting a second driving signal to the piezoelectric pump to be calibrated under the maximum voltage amplitude and the maximum duty ratio, and setting the driving voltage frequency of the second driving signal to be M different preset frequency values respectively to obtain a second flow value output by the piezoelectric pump to be calibrated under each preset frequency value, wherein the M preset frequency values are monotonically increased within the working range of the driving voltage frequency.
It should be noted that the operating range refers to a range formed from the minimum value to the maximum value of the frequency of the driving voltage at which the piezoelectric pump to be calibrated can operate.
Wherein M is 20-40. It should be noted that M is not limited to the above-mentioned range, and may be set as needed.
In one specific example, the maximum voltage amplitude is 7V. The maximum duty cycle is 50%. It should be noted that the maximum voltage amplitude and the maximum duty cycle are related to the performance of the piezoelectric pump to be calibrated, and the maximum voltage amplitude and the maximum duty cycle of different piezoelectric pumps to be calibrated are different.
In one specific example, the driving voltage frequency is in the range of 25KHz to 27 KHz. Further, the M preset frequency values are monotonically increased in 0.05KHz steps within the operating range of the driving voltage frequency.
It should be noted that the driving signal with the preset value of each driving voltage frequency needs to be maintained for a certain time to ensure that the output second flow value is stable. Wherein the driving signal of the preset value of each driving voltage frequency needs to be maintained for 1.5 seconds. Wherein the first 1 second is used to stabilize the second flow value and the second 0.5 second is used to collect data for the second flow value.
S102, comparing the second flow value corresponding to each driving voltage frequency, wherein if the second flow value can satisfy the formula corresponding to F2, the driving voltage frequency corresponding to the second flow value is the preset driving voltage frequency.
It should be noted that, if the second flow rate value corresponding to each preset frequency value is less than F1, the flow rate calibration fails.
By the method for searching the preset driving voltage frequency, the problem that when a plurality of piezoelectric pumps use a single frequency, the control precision is influenced due to insufficient output flow or overlarge output flow of part of the piezoelectric pumps can be avoided. It should be noted that, in actual operation, there is a certain error between the actually obtained F2 of the piezoelectric pump to be calibrated and the F2 calculated according to the formula F2= F1 × (1 + η) with a preset η, where the error is denoted as E, and the requirement of the preset driving voltage frequency is still met when the error is-5% to E ≦ 5%, that is, (F2 25)Practice of- F2Computing）/ F2Computing= E, -5% or more and E5% or less, wherein F2Practice ofIs a reality ofObtaining F2, F2 of the piezoelectric pump to be calibratedComputingF2 is calculated by presetting η and according to the formula F2= F1 × (1 + η). It should be noted that, the preset driving voltage frequency is not limited to be found through the above steps, and may be obtained by using a bisection method within the frequency range recommended by the piezoelectric pump manual. However, since the frequency and the output flow rate may not have a monotonic relationship, the feasibility and efficiency of the dichotomy are lower than those of the above method for finding the preset driving voltage frequency.
S120, determining a calibration relation according to the performance index and the first flow value, wherein the calibration relation is a corresponding relation between the performance index and the first flow value under the driving voltage frequency.
The piezoelectric pump to be calibrated outputs a first flow value at a value taking point of the performance index. In other words, a value-taking point of the performance indicator corresponds to a first flow value. The calibration relationship is a corresponding relationship table of the performance index and the first flow value.
In one embodiment, after the step of determining the calibration relationship according to the performance indicator and the first flow value, the method further includes the step of verifying the calibration relationship: and comparing the N first flow values corresponding to the N preset values, wherein if the variation trend of the N first flow values is consistent with the variation trend of the corresponding N first preset values, the calibration relation is effective. The effectiveness and the accuracy of the calibration of the piezoelectric pump can be ensured by verifying the calibration relation.
In a specific example, if the N preset values monotonically increase within the preset range of the performance index, and the corresponding N first flow values monotonically increase, the calibration relationship is valid.
It should be noted that, if the variation trend of the N first flow rate values is not consistent with the variation trend of the corresponding N first preset values, the calibration relationship is invalid, and the flow rate calibration fails. For example, if the N first preset values are monotonically increasing, and the corresponding N first flow values are monotonically decreasing or non-monotonically changing, the calibration relationship is invalid.
S130, determining a standard value of a corresponding performance index of the piezoelectric pump to be calibrated under the target flow according to the calibration relation, and then measuring a flow value output by the piezoelectric pump to be calibrated under the preset driving voltage frequency and the standard value to obtain the calibrated flow of the piezoelectric pump to be calibrated.
Specifically, a standard value of a performance index corresponding to the piezoelectric pump to be calibrated under the target flow rate is determined according to the calibration relation, then a third driving signal is input to the piezoelectric pump to be calibrated, the frequency of the third driving signal is set to be a preset driving frequency, the performance index of the third driving signal is set to be a preset value, and flow values output by the piezoelectric pump to be calibrated under the preset driving voltage frequency and the standard value are collected to obtain the calibrated flow rate of the piezoelectric pump to be calibrated. The step of determining the standard value of the performance index corresponding to the piezoelectric pump to be calibrated under the target flow according to the calibration relation comprises the following steps: and determining the range of the standard value of the performance index corresponding to the piezoelectric pump to be calibrated under the target flow according to the standard relation, and then calculating through linear interpolation to obtain the standard value of the performance index corresponding to the piezoelectric pump to be calibrated under the target flow.
In one particular example, the piezoelectric pump to be calibrated is a piezoelectric pump model MZB1001T 02. The preset driving voltage frequency is 25.65 KHz. The performance index is the duty ratio, and the calibration relationship between the performance index and the first flow value is shown in table 1. Table 1 shows the calibration of a MZB1001T02 model piezoelectric pump at a preset drive voltage frequency of 25.65 KHz. The target flow rate was 80 mL/min. As can be seen from table 1, the standard value of the performance index of the piezoelectric pump to be calibrated under the target flow rate of 80mL/min is between 35% and 40%, and then the standard value calculated by linear interpolation is 35.66%. And then, measuring the flow value output by the piezoelectric pump to be calibrated under the preset driving voltage frequency (namely 25.65 KHz) and the standard value (namely 35.66%) by using a flow detector to be 80.05mL/min, namely the flow of the piezoelectric pump to be calibrated after calibration.
TABLE 1
Duty cycle First flow value (mL/min)
5% 0.23
10% 1.05
15% 3.19
20% 11.66
25% 22
30% 45.8
35% 78.1
40% 102.3
45% 110.2
50% 123.3
According to the flow calibration method of the piezoelectric pump, N first flow values output by the piezoelectric pump to be calibrated within a preset range of performance indexes are measured under the preset driving voltage frequency, the performance indexes are voltage amplitude values or duty ratios, a corresponding relation between the performance indexes and the first flow values is established, and then the calibrated flow is obtained by calibrating each piezoelectric pump through the corresponding relation, so that the problem that response time and fluctuation degree of a control system are uncertain due to large individual performance difference of the piezoelectric pump is solved, and consistency of control effects of different piezoelectric pumps is improved.
According to the flow calibration method of the piezoelectric pump, the individual difference of the piezoelectric pump is made up by performing two-dimensional calibration on the voltage frequency and the voltage amplitude of each piezoelectric pump in advance, so that the problem that the response time and the fluctuation degree of a control system are uncertain due to large individual performance difference of the piezoelectric pump is solved, the consistency of the control effects of different piezoelectric pumps is improved, the control effects of different piezoelectric pumps are consistent, and the consistency of the performance of equipment with the piezoelectric pumps as core components is ensured.
Further, the flow calibration method of the piezoelectric pump can accelerate the response speed and shorten the time for controlling the flow to enter the steady state through the calibration of the point-by-point duty ratio or the voltage amplitude.
In conclusion, the research develops the flow calibration method of the piezoelectric pump for the first time, can improve the consistency of the control effects of different piezoelectric pumps, and enables the control effects of different piezoelectric pumps to be consistent, so that the consistency of the performance of equipment with the piezoelectric pump as a core component is ensured, and the method is suitable for wide popularization.
As shown in fig. 1, a flow calibration system 100 of a piezoelectric pump according to an embodiment can perform flow calibration on a piezoelectric pump 101 to be calibrated according to the flow calibration method of the piezoelectric pump according to the above embodiment, so as to improve consistency of control effects of different piezoelectric pumps.
Specifically, the flow calibration system 100 of the piezoelectric pump includes a control module 110 and a flow detection module 120. The control module 110 can apply a drive signal to the piezoelectric pump 101 to be calibrated to drive the piezoelectric pump 101 to be calibrated, and can control the drive voltage frequency and the performance index of the drive signal. The flow detection module 120 is coupled to the control module 110. The flow rate detection module 120 is configured to detect a flow rate value of the piezoelectric pump 101 to be calibrated, and transmit the detected flow rate value of the piezoelectric pump 101 to be calibrated to the control module 110. Wherein, the performance index is a voltage amplitude or a duty ratio.
The control module 110 can control the voltage frequency of the driving signal to be a preset driving voltage frequency, and can control the performance index of the driving signal to be in a preset range to drive the piezoelectric pump 101 to be calibrated; the flow rate detection module 120 is capable of determining N first flow rate values output by the piezoelectric pump 101 to be calibrated within a preset range of a preset driving voltage frequency and a preset performance index, and transmitting the N first flow rate values to the control module 110. The control module 110 can determine a calibration relationship based on the performance metric and the first flow value. The control module 110 can determine a standard value of a performance index corresponding to the target flow rate of the piezoelectric pump 101 to be calibrated according to the calibration relationship, then can control the driving voltage frequency of the driving signal to be a preset driving voltage frequency, and control the performance index of the driving signal to be the standard value, drive the piezoelectric pump 101 to be calibrated, and obtain the calibrated flow rate of the piezoelectric pump 101 to be calibrated through the flow rate detection module 120.
The control module 110 can also verify the validity of the calibration relationship, among other things.
The control module 110 is further capable of transmitting a second driving signal with a maximum voltage amplitude and a maximum duty ratio to the piezoelectric pump 101 to be calibrated, and setting the driving voltage frequency of the second driving signal to M different preset frequency values, respectively, so as to drive the piezoelectric pump 101 to be calibrated; the flow rate detection module 120 is further capable of determining a second flow rate value output by the piezoelectric pump 101 to be calibrated at each preset frequency value, and transmitting the second flow rate value to the control module 110; the control module 110 can also compare the second flow value corresponding to each driving voltage frequency to obtain a preset driving voltage frequency.
Wherein, the flow detection module 120 can be connected with the piezoelectric pump 101 to be calibrated.
In one particular example, the flow detection module 120 is a flow sensor. The flow rate detection module 120 is not limited to a flow rate sensor, and may be another module for detecting the flow rate of the piezoelectric pump.
In one embodiment, the flow calibration system 100 of the piezoelectric pump further comprises a display module 130. The display module 130 is connected to the control module 110. The display module 130 can generate a start calibration command or a stop calibration command to the control module 110. The display module 130 can receive and display the signal transmitted by the control module 110. Further, the display module 130 can also be connected with the flow detection module 120. The display module 130 can receive and display the signal transmitted by the flow detection module 120. It should be noted that the display module 130 may be omitted, and in this case, the start calibration instruction or the stop calibration instruction may be generated to the control module 110 by other conventional manners in the art.
In one embodiment, the flow calibration system 100 of the piezoelectric pump further comprises a memory module 140. The storage module 140 is connected to the control module 110. The storage module 140 can receive and store the calibration relationship transmitted by the control module 110. In this case, the control module 110 may have a storage function.
The flow calibration system 100 of the piezoelectric pump performs a flow calibration on the piezoelectric pump 101 to be calibrated as follows:
(1) the operator sends an instruction to the control module 110 via the display module 130 that a start calibration has occurred. After the control module 110 receives the calibration starting instruction, the control module 110 transmits a second driving signal with the maximum voltage amplitude and the maximum duty ratio to the piezoelectric pump 101 to be calibrated, and sets the driving voltage frequency of the second driving signal to M different preset frequency values respectively so as to drive the piezoelectric pump 101 to be calibrated; the flow rate detection module 120 determines a second flow rate value output by the piezoelectric pump 101 to be calibrated at each preset frequency value, and transmits the second flow rate value to the control module 110; next, the control module 110 compares the second flow value corresponding to each driving voltage frequency, and if the second flow value can satisfy the formula corresponding to F2, the driving voltage frequency corresponding to the second flow value is the preset driving voltage frequency. It should be noted that, if the second flow rate value corresponding to each preset frequency value is smaller than F1, the control module 110 generates a flow rate calibration message to the display module 130, and the calibration is terminated. It should be noted that, in actual operation, there is a certain relationship between the actually obtained F2 of the piezoelectric pump to be calibrated and the F2 calculated by presetting η and according to the formula F2= F1 × (1 + η)The error is recorded as E, when the error is more than or equal to-5% and less than or equal to 5%, the requirement of the preset driving voltage frequency is still met, namely (F2)Practice of- F2Computing）/ F2Computing= E, -5% or more and E5% or less, wherein F2Practice ofF2, F2 for the actual piezoelectric pump to be calibratedComputingF2 is calculated by presetting η and according to the formula F2= F1 × (1 + η).
(2) After finding the preset driving voltage frequency, the control module 110 controls the voltage frequency of the driving signal to be the preset driving voltage frequency, controls the performance index of the driving signal to be in a preset range, and drives the piezoelectric pump 101 to be calibrated; the flow rate detection module 120 measures N first flow rate values output by the piezoelectric pump 101 to be calibrated within a preset range of a preset driving voltage frequency and a preset performance index, and transmits the N first flow rate values to the control module 110.
(3) The control module 110 determines a calibration relationship based on the performance metric and the first flow value. The control module 110 verifies the calibration relationship and transmits the valid calibration relationship to the storage module 140 for storage. It should be noted that, if the variation trend of the N first flow rate values is not consistent with the variation trend of the corresponding N first preset values, the calibration relationship is invalid, and the control module 110 generates the flow rate calibration information to the display module 130, and the calibration is terminated.
(4) After determining the effective calibration relationship, the control module 110 determines a standard value of the performance index corresponding to the target flow rate of the piezoelectric pump 101 to be calibrated according to the calibration relationship, then controls the driving voltage frequency of the driving signal to be the preset driving voltage frequency, controls the performance index of the driving signal to be the standard value, drives the piezoelectric pump 101 to be calibrated, and obtains the calibrated flow rate of the piezoelectric pump 101 to be calibrated through the flow rate detection module 120.
The flow calibration system 100 of the piezoelectric pump measures N first flow values output by the piezoelectric pump 101 to be calibrated within a preset range of a performance index through the control module 110 and the flow detection module 120 under a preset driving voltage frequency, where the performance index is a voltage amplitude or a duty ratio, and accordingly establishes a corresponding relationship between the performance index and the first flow value, and then calibrates each piezoelectric pump through the corresponding relationship to obtain a calibrated flow, so as to solve the problem that response time and fluctuation degree of the control system are uncertain due to large individual performance difference of the piezoelectric pump, and improve consistency of control effects of different piezoelectric pumps.
The following are specific examples:
example 1
Three calibration piezoelectric pumps to be tested are respectively numbered as a pump No. 1, a pump No. 2 and a pump No. 3. The model of each piezoelectric pump to be calibrated is MZB1001T02, the output flow of the piezoelectric pump is required to be controllable within the range of 0-100 mL/min, and therefore F1 is 100 mL/min. The flow calibration system for a piezo pump is shown in figure 1.
The flow calibration process of each piezoelectric pump to be calibrated is as follows:
(1) the operator sends an instruction to the control module 110 via the display module 130 that a start calibration has occurred. After the control module 110 receives the start calibration instruction, the control module 110 transmits a second driving signal with a maximum voltage amplitude (7V) and a maximum duty ratio (50%) to the piezoelectric pump to be calibrated, and sets the driving voltage frequency of the second driving signal to 40 different preset frequency values in a step-size increment of 0.05KHz within the range of 25KHz to 27KHz so as to drive the piezoelectric pump to be calibrated; the flow rate detection module 120 determines a second flow rate value output by the piezoelectric pump to be calibrated at each preset frequency value, and transmits the second flow rate value to the control module 110; next, the control module 110 compares the second flow value corresponding to each driving voltage frequency, and if the second flow value can satisfy the formula corresponding to F2, the driving voltage frequency corresponding to the second flow value is the preset driving voltage frequency. It should be noted that, if the second flow rate value corresponding to each preset frequency value is smaller than F1, the control module 110 generates a flow rate calibration message to the display module 130, and the calibration is terminated. It should be noted that, in actual operation, there is a certain error between the actually obtained F2 of the piezoelectric pump to be calibrated and the F2 calculated according to the formula F2= F1 × (1 + η) with a preset η, where the error is denoted as E, and the requirement of the preset driving voltage frequency is still met when the error is-5% to E ≦ 5%, that is, (F2 25)Practice of- F2Computing）/ F2Computing= E, -5% or more and E5% or less, wherein F2Practice ofIs a reality ofObtaining F2, F2 of the piezoelectric pump to be calibratedComputingF2 is calculated by presetting η and according to the formula F2= F1 × (1 + η). Wherein eta is 20%, and F2 is calculated according to the above formulaComputingIf =120mL/min, F2Practice ofCan meet the requirement between 114 mL/min and 126 mL/min. F2 for Pump No. 1, Pump No. 2, and Pump No. 3 of this examplePractice ofThe corresponding driving voltage frequencies are respectively 25.65KHz, 25.35KHz and 26.05KHz, namely the preset voltage frequencies of the No. 1 pump, the No. 2 pump and the No. 3 pump.
(2) After finding the preset driving voltage frequency, the control module 110 controls the voltage frequency of the driving signal to be the preset driving voltage frequency, controls the performance index of the driving signal within a preset range, and drives the piezoelectric pump 101 to be calibrated. The flow rate detection module 120 determines 10 first flow rate values output by the piezoelectric pump to be calibrated within a preset range of a preset driving voltage frequency and a preset performance index, and transmits the 10 first flow rate values to the control module 110. In the embodiment, the performance index of the driving signal is a duty ratio, and the preset range is 0% -50%. Within the preset range of the performance index, the step length is 5% and monotonously increased, so that 10 first flow values corresponding to 10 individual performance indexes are obtained.
(3) The control module 110 determines a calibration relationship based on the performance metric and the first flow value. The control module 110 verifies the calibration relationship and transmits the valid calibration relationship to the storage module 140 for storage. It should be noted that, if the variation trend of the 10 first flow rate values is not consistent with the variation trend of the corresponding 10 first preset values, the calibration relationship is invalid, and the control module 110 generates the flow rate calibration information to the display module 130, and the calibration is terminated. The calibration relationship of pump # 1 at a preset driving voltage frequency of 25.65KHz is shown in table 1. The calibration of pump No. 2 at a preset drive voltage frequency of 25.35KHz is shown in table 2. The calibration of pump # 3 at a preset drive voltage frequency of 26.05KHz is shown in table 3.
TABLE 22 Pump calibration at a preset drive Voltage frequency of 25.35KHz
Duty cycle First flow value (mL/min)
5% 0.63
10% 0.98
15% 1.25
20% 3.74
25% 12.61
30% 20.57
35% 35.1
40% 61.3
45% 91.5
50% 114.9
TABLE 33 CALIBRATION OF PUMP AT PRE-SETTING DRIVE VOLTAGE FREQUENCY 26.05KHz
Duty cycle First flow value (mL/min)
5% 0.22
10% 0.41
15% 0.67
20% 1.83
25% 9.15
30% 16.54
35% 32.34
40% 62.26
45% 98.77
50% 123.5
(4) After determining the effective calibration relationship, the control module 110 determines a standard value of a performance index corresponding to the target flow rate of the piezoelectric pump to be calibrated according to the calibration relationship, then controls the driving voltage frequency of the driving signal to be the preset driving voltage frequency, controls the performance index of the driving signal to be the standard value, drives the piezoelectric pump to be calibrated, and obtains the calibrated flow rate of the piezoelectric pump to be calibrated through the flow rate detection module 120. Specifically, the target flow rate was 80 mL/min. As can be seen from tables 1 to 3, the standard values of the performance indexes (i.e., duty ratios) of the pumps 1 to 3 at the target flow rate of 80mL/min are respectively 35% to 40%, 40% to 45%, and the standard values of the pumps 1 to 3 calculated by linear interpolation are respectively 35.66%, 43.1%, and 42.43%. Then, the flow detection module 120 is adopted to determine that the output flow value of the No. 1 to No. 3 pump under the corresponding preset driving voltage frequency and the corresponding standard value is the calibrated flow of the No. 1 to No. 3 pump. The calibrated flow rates of pump No. 1, pump No. 2 and pump No. 3 were 80.05mL/min, 80.02mL/min and 79.9mL/min, respectively. Therefore, the flow calibration method for the piezoelectric pump according to the above embodiment calibrates the piezoelectric pump to improve the consistency of the control effects of different piezoelectric pumps, so as to effectively solve the problem of poor consistency of the control effects caused by individual differences of the piezoelectric pumps.
And (3) testing:
and respectively carrying out closed-loop control on the three piezoelectric pumps to be calibrated before and after calibration, wherein the closed-loop control effect is shown in figures 2-3. Fig. 2 shows the closed-loop control effect of three piezoelectric pumps to be calibrated before calibration. Fig. 3 shows the closed-loop control effect of the three piezoelectric pumps to be calibrated after being calibrated by the above calibration process.
As can be seen from fig. 2, the response time of the three piezoelectric pumps to be calibrated before calibration is longer, and the flow rate values under the same response time are obviously different. As can be seen from fig. 3, the response time of the three piezoelectric pumps to be calibrated after calibration is shorter than the response time before calibration, and the flow values after calibration are substantially consistent under the same response time, which illustrates that the piezoelectric pumps are calibrated by the flow calibration method of the piezoelectric pump according to the above embodiment, so as to improve the consistency of the control effects of different piezoelectric pumps, and effectively solve the problem of poor consistency of the control effects caused by individual differences of the piezoelectric pumps.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A flow calibration method for a piezoelectric pump is characterized by comprising the following steps:
under a preset driving voltage frequency, measuring N first flow values output by the piezoelectric pump to be calibrated within a preset range of a performance index, wherein the piezoelectric pump to be calibrated meets the following formula under the preset driving voltage frequency: f2= F1 × (1 + η), where F2 is a maximum flow rate output by the piezoelectric pump to be calibrated at the preset driving voltage frequency, F1 is a rated flow rate of the piezoelectric pump to be calibrated, η is a flow rate increase percentage, and the performance index is a voltage amplitude or a duty ratio;
determining a calibration relation according to the performance index and the first flow value, wherein the calibration relation is a corresponding relation between the performance index and the first flow value under the driving voltage frequency; and
and determining a standard value of the performance index corresponding to the piezoelectric pump to be calibrated under the target flow according to the calibration relation, and then measuring the flow value output by the piezoelectric pump to be calibrated under the preset driving voltage frequency and the standard value to obtain the calibrated flow of the piezoelectric pump to be calibrated.
2. The method for calibrating the flow rate of a piezoelectric pump according to claim 1, wherein the step of determining N first flow rate values output by the piezoelectric pump to be calibrated within a preset range of performance indexes at a preset driving voltage frequency comprises: inputting a first driving signal to the piezoelectric pump to be calibrated, setting the voltage frequency of the first driving signal as the preset driving voltage frequency, and setting the performance index of the first driving signal as N different preset values respectively, to obtain the first flow value output by the piezoelectric pump to be calibrated at each preset value, where the N preset values are monotonously changed within the preset range of the performance index.
3. The method for calibrating the flow rate of a piezoelectric pump according to claim 2, wherein the N preset values monotonically increase over the preset range of the performance level.
4. The method for calibrating the flow rate of a piezoelectric pump according to claim 2, wherein the preset range is an operating range of the performance index of the piezoelectric pump to be calibrated.
5. The method for calibrating the flow rate of a piezoelectric pump according to any one of claims 2 to 4, wherein the step of determining the calibration relationship based on the performance index and the first flow rate value further comprises the step of verifying the calibration relationship: and comparing the N first flow values corresponding to the N preset values, wherein if the variation trend of the N first flow values is consistent with the variation trend of the N corresponding first preset values, the calibration relation is valid.
6. The method for calibrating the flow rate of a piezoelectric pump according to any one of claims 1 to 4, wherein before the step of determining the N first flow rate values output by the piezoelectric pump to be calibrated within the preset range of the performance index at the preset driving voltage frequency, the method further comprises the step of searching for the preset driving voltage frequency:
under the conditions of the maximum voltage amplitude and the maximum duty ratio, measuring M second flow values output by the piezoelectric pump to be calibrated in the working range of the driving voltage frequency; and
comparing the second flow value corresponding to each driving voltage frequency, wherein if the second flow value can satisfy the formula corresponding to F2, the driving voltage frequency corresponding to the second flow value is the preset driving voltage frequency.
7. The method for calibrating the flow rate of a piezoelectric pump according to claim 6, wherein the step of determining the M second flow rate values output by the piezoelectric pump to be calibrated in the operating range of the driving voltage frequency under the maximum voltage amplitude and the maximum duty cycle comprises: and inputting a second driving signal to the piezoelectric pump to be calibrated under the maximum voltage amplitude and the maximum duty ratio, and setting the driving voltage frequency of the second driving signal to M different preset frequency values respectively, so as to obtain the second flow value output by the piezoelectric pump to be calibrated under each preset frequency value, wherein the M preset frequency values are monotonically increased within the working range of the driving voltage frequency.
8. A flow calibration system for a piezoelectric pump, comprising:
the control module can apply a driving signal to the piezoelectric pump to be calibrated to drive the piezoelectric pump to be calibrated, and can control the driving voltage frequency and the performance index of the driving signal, wherein the performance index is the voltage amplitude or the duty ratio; and
the flow detection module is connected with the control module and is used for detecting the flow value of the piezoelectric pump to be calibrated and transmitting the detected flow value of the piezoelectric pump to be calibrated to the control module;
the control module can control the voltage frequency of the driving signal to be a preset driving voltage frequency, and can control the performance index of the driving signal to be in a preset range to drive the piezoelectric pump to be calibrated, the flow detection module can determine N first flow values output by the piezoelectric pump to be calibrated in the preset driving voltage frequency and the preset range of the performance index, and transmit the N first flow values to the control module, and the piezoelectric pump to be calibrated satisfies the following formula at the preset driving voltage frequency: f2= F1 × (1 + η), where F2 is the maximum flow rate output by the piezoelectric pump to be calibrated at the preset driving voltage frequency, F1 is the rated flow rate of the piezoelectric pump to be calibrated, and η is the percentage of flow rate increase; the control module can determine a calibration relation according to the performance index and the first flow value, wherein the calibration relation is a corresponding relation between the performance index and the first flow value under the driving voltage frequency; the control module can determine a standard value of the performance index corresponding to the piezoelectric pump to be calibrated under the target flow according to the calibration relation, then can control the driving voltage frequency of the driving signal to be the preset driving voltage frequency, control the performance index of the driving signal to be the standard value, drive the piezoelectric pump to be calibrated, and obtain the calibrated flow of the piezoelectric pump to be calibrated through the flow detection module.
9. The system for calibrating the flow rate of a piezoelectric pump according to claim 8, further comprising a display module, wherein the display module is connected to the control module, and the display module can generate a start calibration command or a stop calibration command to the control module and can receive and display a signal transmitted by the control module.
10. The system for calibrating the flow rate of a piezoelectric pump according to any one of claims 8 to 9, further comprising a storage module connected to the control module, wherein the storage module is capable of receiving and storing the calibration relationship transmitted by the control module.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2874440Y (en) * 2005-05-08 2007-02-28 上海烟草（集团）公司 Flow meter correcting system
CN101126384A (en) * 2007-08-17 2008-02-20 吉林大学 Method for exactly controlling output quantity of piezoelectric pump
JP2008248851A (en) * 2007-03-30 2008-10-16 Ihi Corp Flow rate control method and device for pump device
CN107014468A (en) * 2017-03-02 2017-08-04 浙江省计量科学研究院 Compressed gas-driven liquid runoff calibration device and its calibration method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2874440Y (en) * 2005-05-08 2007-02-28 上海烟草（集团）公司 Flow meter correcting system
JP2008248851A (en) * 2007-03-30 2008-10-16 Ihi Corp Flow rate control method and device for pump device
CN101126384A (en) * 2007-08-17 2008-02-20 吉林大学 Method for exactly controlling output quantity of piezoelectric pump
CN107014468A (en) * 2017-03-02 2017-08-04 浙江省计量科学研究院 Compressed gas-driven liquid runoff calibration device and its calibration method

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